feat: move to mystmd #2270

Job	Run time
change-detection / Identify source changes	10s
rr-tests / Action	18s
cookie / Distribution build	10m 36s
rr-tests / Run cog on README	12s
cookie / Check included Noxfile	3m 52s
rr-tests / Run pylint	14s
cookie / Format	9m 52s
cookie / Check Python 3.10 on macos-latest	2m 26s
cookie / Check Python 3.14 on macos-15-intel	5m 10s
cookie / Check Python 3.14 on ubuntu-latest	3m 45s
cookie / Check Python pypy-3.11 on ubuntu-latest	2m 9s
cookie / Check Python 3.14 on windows-latest	4m 21s
cookie / Check Python 3.10 on macos-15-intel	4m 2s
rr-tests / Check Python 3.10 on macos-15-intel	1m 10s
rr-tests / Check Python 3.10 on ubuntu-latest	34s
rr-tests / Check Python 3.10 on macos-latest	38s
rr-tests / Check Python 3.10 on windows-latest	44s
cookie / Check Python 3.10 on windows-latest	3m 36s
cookie / Check Python 3.10 on ubuntu-latest	3m 51s
rr-tests / Check Python 3.12 on macos-latest	37s
cookie / Check Python 3.14 on macos-latest	1m 46s
rr-tests / Check Python 3.14 on ubuntu-latest	38s
rr-tests / Check Python 3.12 on windows-latest	43s
rr-tests / Check Python 3.14 on macos-latest	27s
rr-tests / Check Python 3.14 on macos-15-intel	1m 3s
rr-tests / Check Python 3.12 on ubuntu-latest	32s
rr-tests / Check Python 3.12 on macos-15-intel	1m 35s
rr-tests / Check Python 3.14 on windows-latest	1m 6s
cookie / pass	3s
pass	5s
	1h 6m 15s

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